Pollution and sexually transmitted infections (STIs) are making humans sterile. At least that’s the case in the dystopian world of The Handmaid’s Tale, where the heroine Offred is forced to live as a concubine under a dictatorship – one of the ‘handmaids’ made to reproduce to keep the birth rate up.

While the book, and subsequent hugely successful television series, can be dismissed as pure fiction, the causes for infertility aren’t far off the truth. In the real world, infertility is becoming a major problem in the West. The finger is being pointed at diseases like chlamydia, and environmental factors such as pollution. Fiction seems like it’s becoming fact.

Women traditionally shouldered the blame for infertility – after all, they are the ones who are born with a finite number of eggs. Once these are gone, the biological clock stops ticking and the menopause hits, whereas men produce a completely fresh batch of semen about every 12 weeks (this is how long it takes for sperm to fully mature). But men also have a ticking clock, and they aren’t as virile as they used to be.

Last year, a team of researchers led by Dr Hagai Levine published a study in Human Reproduction Update. They said sperm counts in the West have more than halved in the past 40 years and are dropping by an average of 1.4 per cent every year, with no sign of abating. Their results showed a 52 per cent drop in sperm concentration, and a 59 per cent decline in total sperm count, among men from North America, Europe, Australia and New Zealand.

Dr Shanna Swan, who was part of the team, says that human-made compounds are partly to blame: “There is a large literature showing that chemicals in the environment and the workplace can decrease semen quality, including concentration. The most dramatic of these are occupational, because the doses are higher, but there is also a lot of data on, for example, pesticides, heavy metals and plasticisers.”

The plastic problem

Chemicals called phthalates are found in plastics all around us – from food packaging to fragrance, cleaning products to cosmetics, and shower curtains to car dashboards. About 450,000,000kg of phthalates are produced every year and are used to make plastics more flexible, transparent and durable, and we may inadvertently consume them when we eat food that has come into contact with phthalate-containing packaging. Phthalates are so ubiquitous that they can be detected in the urine of about 95 per cent of us.

More like this

Phthalates have been linked to all sorts of health conditions, including infertility. As far back as 2003, a study showed that exposure of lab rats to certain phthalates during pregnancy affected the development of the testes of the offspring. Since then, various animal studies have found similar results, which led some scientists to suggest the same might be true in humans. A Swedish study, published in the journal Environmental Health Perspectives in 2015, claimed that phthalates caused genital birth defects in boys and…

This is an extract from issue 321 of BBC Focus magazine. Subscribe and get the full article delivered to your door, or download the BBC Focus app to read it on your smartphone or tablet. Find out more

Follow Science Focus on Twitter, Facebook, Instagram and Flipboard